Geometry and Electronic Properties of Glycerol Adsorbed on Bare and

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Geometry and Electronic Properties of Glycerol Adsorbed on Bare and Transition-Metal Surface-Alloyed Au(111): a Density Functional Theory Study Jonas Baltrusaitis, Mikael Valter, and Anders Hellman J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.5b11544 • Publication Date (Web): 23 Dec 2015 Downloaded from http://pubs.acs.org on January 9, 2016

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The Journal of Physical Chemistry

Geometry and Electronic Properties of Glycerol Adsorbed on Bare and Transition-metal Surface-alloyed Au(111): a Density Functional Theory study Jonas Baltrusaitis1,* Mikael Valter2 and Anders Hellman2,* 1

Department of Chemical and Biomolecular Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015, USA 2

Department of Applied Physics, Chalmers University of Technology, SE-41296 Göteborg, Sweden

Abstract Glycerol exists in large amounts owing to its role as a by-product in biodiesel production, and thanks to its chemical composition it can be converted into more high-value products, such as mono- and poly- ethers, esters, diols, acrolein and others. Hence, predicting glycerol reactive properties is of utmost importance in order to designing efficient catalytic processes for its selective (electro)catalytic transformations, however, such an understanding is still far from complete. In this work, we performed quantum chemical calculations to validate a range of dispersion corrected functionals to accurately predict and interpret structural, electronic and vibrational properties of glycerol adsorbed on bare and transition-metal surface-alloyed Au(111) surface.

optB86b-vdW was found to have the overall best agreement with experiments

concerning lattice constant, bulk stress, surface energy and methanol adsorption among PBE, optB88-vdW, optPBE-vdW, vdW-DF, vdW-DF2 and vdW-BEEF. Glycerol adsorption energy is found to correlate well with the calculated d-band center of the transition-metal containing Au(111) surface layer. O-H stretching vibrations are found to be very sensitive of the surfacealloy atom and resulted in large shifts towards lower wavenumbers, when compared to those on bare Au(111). The latter results clearly show that adsorption of glycerol to surface-alloy atoms can be monitored in situ by infrared spectroscopy. *Corresponding authors: [email protected], (610)758-6837; [email protected], +46 317725611

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Introduction Crude glycerol is a major byproduct of the biodiesel production and its sustainable utilization is of tremendous interest using both thermochemical and biological methods alike.1 Projected production of biodiesel in 2016 is 37 billion gallons with the corresponding generated glycerol amount of 4 billion gallons.2 This recent abundance of glycerol enabled its use as a ‘platform molecule’3–5 to produce variety of commodity chemicals.6 Single step catalytic dehydration on acidic catalysts,7 hydrogenolysis and selective oxidation on noble metal based catalysts8,9 are currently the primary methods of glycerol utilization.10 Additionally syngas (CO+H2) generation via steam, autothermal and aqueous phase reforming are promising routes of catalytic glycerol conversion into hydrogen or other chemicals.11,12 Finally, photoelectrochemical (PEC) hydrogen production from aqueous solutions of organic wastewater streams, including glycerol, is of great importance as it is much more efficient thermodynamically than the competing water splitting reaction.13,14 Gold (Au), in the shape of supported nanoparticles on carbon, has been used as a model oxidation catalyst in many glycerol electrooxidation studies15–17 and with high current densities yields.13 Additionally, Au has been shown to be an efficient conventional glycerol oxidation catalyst to value added products.18–22 Finally, some of these catalytic processes involved bimetallic Au catalysts, including Pd/Au,20,23,24 Pt/Au,18,23–25 Ru/Au.26 Hence, gold is of great interest in designing an efficient glycerol (electro)oxidation catalyst and has been used in the past to elucidate experimentally microscopic level information of glycerol transformation.16,27,28 At the atomic level, Au(111) has long been used as a convenient infinite, perfect, atomically flat closepacked face-centered-cubic (fcc) surface model, and although the 22x√3 reconstruction is wellknown the actual effect on adsorption energies are estimated to be less than 0.1 eV.29 Interactions of organic molecules, such as glycerol and its reactive intermediates and products, with Au(111) surface range from noncovalent (physisorption) to covalent (chemisorption) and put constraints on the computational modeling methods, such as Density Functional Theory (DFT), typically used to understand the elementary surface reactions responsible for the catalytic transformations. Long-range interaction that govern physisorption is not accounted for in the conventional generalized gradient approximation (GGA) level of theory30, and thus, binding energies are underestimated whereas equilibrium distances are overestimated.31 For example, use of vdW corrected functionals (optB86b-vdW and vdW-DF) yielded increased adsorption energies 2 ACS Paragon Plus Environment

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and reduced the equilibrium distances for adsorbed isooctane and ethanol on Fe(100).31 Further, conjugated organic molecules interact only weakly with metal (Au, Pt) (111) surfaces, if no dispersion corrections are applied, resulting in erroneous estimated adsorption energies.32 In general, there are two different approaches to treat the nonlocal vdW interactions. First, an additive atom pairwise potential of the form C6R-6, where C6 is an atom-specific parameter determining the interaction strength between two atoms and R is the separation between two atoms, is added to the GGA functional to provide for the expected asymptotic behavior.30,33 It has been noted that this approach becomes challenging when studying adsorption on metal surfaces and polarizability thereof.34 Second, a pure density functional formulation (vdW-DF),35 which is consistent both for short and long range interactions.30 Several version of this formulation are available but the exact evaluation of their performance related to various organic molecule adsorption on Au(111) is limited.30 In this work we investigated the performance of different density functionals, both vdW uncorrected (PBE) and corrected (optB86b-vdW, optB88-vdW, optPBE-vdW, vdW-DF, vdWDF2 and vdW-BEEF) in predicting structural, electronic and vibrational properties of glycerol adsorbed on Au(111) as well as elucidating changes caused by the presence of the transitionmetal (TM) alloy atoms. This work was motivated by the need to establish an appropriate computational method to further elucidate complex mechanistic transformations of glycerol, especially on complex bimetallic Au containing surfaces. Bimetallic noble metal systems have been shown to be more reactive towards certain glycerol transformations and less prone to the catalyst poisoning,20,26 while certain non-noble TM, such as Ni, have been also shown to yield acceptable catalytic performance.36 As a first step, we studied a wide range of alloy atoms substituted into the Au(111) surface to explore important electronic structure and adsorption geometry changes, potentially affecting reactivity of the adsorbed glycerol. The results obtained are discussed from the perspective of conventional, as well as electrochemical, catalysis. Theoretical methods. All density functional calculations were performed using VASP37–40. The spin-polarized version of the Perdew-Burke-Ernzerhof (PBE) approximation41,42 was used for evaluating the semi-local exchange and correlation contribution. Several flavors of dispersion corrections were utilized in this work. More specifically, “opt” functionals, optB86b-vdW, optB88-vdW and optPBE-vdW, were used,43,44 as well as vdW-DF and vdW-DF2 versions.35,45 In 3 ACS Paragon Plus Environment


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short, optB86b-vdW, optB88-vdW and optPBE-vdW included long-range correlation in combination with the B86, B88 and PBE exchange, respectively. Both vdW-DF, and vdW-DF2 included long-range correlation in combination with the revPBE and rPW86 exchange, respectively. The vdW-BEEF is a recent development that has the additional benefit of providing a Bayesian estimate of the errors from the functional.46 method

47,48

The projector augmented wave

was used to describe the interaction between valence electrons and the core. The

number of valence electrons for each element was, H atom (1s1), C atom (2s22p2), O atom (2s22p4), and Au atom (10d51s6). The Kohn-Sham orbitals were expanded using plane-waves with a kinetic energy cutoff of 450 eV. An effective temperature of 0.05 eV was used to smear the Fermi discontinuity. The Au(111) surface was modeled in a p(3x3) supercell for adsorption, however, surface energies was calculated using a p(1x1) supercell. The number of layers is restricted to 4 layers for adsorption and 10 layers for surface energies. The periodic surface slabs were separated in the zdirection by a vacuum distance of 20 Å. For the surface cells, the k-point sampling was performed with (6, 6, 1) and (16,16, 1) Monkhorst-Pack grid, respectively, whereas the bulk calculations used a (16,16,16) Monkhorst-Pack grid.49 Gas-phase glycerol structure and vibrational properties were calculated in a large simulation box (20x20x20 Å) using the gamma k-point. The structural relaxations were performed within the quasi-Newton method, using the Hellmann-Feynman theorem for the force calculations. The ionic positions were optimized until the total residual force was less than 0.02 eV/Å. Adsorption energy was calculated with respect to the bare surfaces and glycerol in gas-phase. Zero-point energy corrections were not included in the presented energetics. Negative adsorption energies denote exothermic adsorption. Doping energy, Ealloy, was calculated as (EAu(111)alloy+EAu atom)-(EAu(111)+Ealloy atom). Vibrational modes and frequencies were determined by diagonalization of the Hessian matrix, where the force derivatives were calculated by means of the central difference approximation with a displacement of 0.05 Å. Similarly, the dipole intensities came from the central difference approximation of the gradient of the dipole moment.50

Results and Discussion Geometric parameters and adsorption energies of glycerol on Au(111).

We begin by

investigating calculated ground-state structures and adsorption energies of glycerol on pristine 4 ACS Paragon Plus Environment

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and TM surface-alloyed Au(111), together with an electronic structure analysis using the d-band model.51 First, we explored the functionals effect on the optimized lattice parameter and bulk modules. These data are presented in Table 1. It can be seen that the lattice parameter is overestimated both at the GGA level and with the vdW functionals whereas the bulk modules are underestimated as compared to experiment in all cases. In particular, optB86b-vdW, optB88vdW and optPBE-vdW overestimated the experimental lattice parameter by 1.5%, 2.4% and 2.9 % whereas vdW-DF and vdW-DF2 resulted in 4.3% and 6.5% and vdW-BEEF in 3.6%, which should be compared to the overestimate from PBE of 2.4%. Clearly the optB86b-vdW yielded the smallest overestimation of the experimental lattice parameter.

Similarly, optB86b-vdW

calculated bulk Au modulus was underestimated the least from all the functionals considered and performed even better than conventional uncorrected PBE functional. Next we evaluate how the surface energy of Au(111) depends on the functional. All functionals underestimate the surface energy as compared to experiment,52,53 however, the opt-B86b performs best as compared to all the rest, see Table1. Finally, we calculated methanol adsorption on Au(111) and compared to experimental values.52,53 The results fall into three regimes, where PBE gives the lowest value (0.12 eV), followed by vdW-BEEF, vdW-DF, vdW-DF2 (-0.26 eV, -0.32 eV, -0.34 eV), and then the “opt”-vdW, optPBE-vdW, optB88-vdW, and optB86b-vdW (-0.42 eV, -0.44 eV, -0.45 eV), respectively. Comparing with measurements of methanol adsorption energy of -0.42 eV52,53 it is clear that the “opt”-vdW perform at a sufficient level. We further explored the effect of different xc-functionals with and without long-range dispersion correction on the adsorbed glycerol structure, as shown in Figure 1. The geometry of the glycerol molecule itself was found not to be sensitive to the xc-functional as all functionals investigated yielded C-C distance of 1.53-1.54 Å, O-Cend distance of 1.42-1.47 Å, O-Ccentral distance of 1.431.48 Å, and O-H distance of 0.97-0.99 Å, which compares well with those calculated of glycerol on Pt (100), Pt(110) and Pt (111) of 1.53, 1.44 and 0.98 Å, respectively.54. The glycerol-Au(111) surface distance was strongly affected by the use of dispersion correction. Glycerol was found to bind on Au(111) via terminal oxygen lone pair, consistently with the adsorption mode found for other precious metal – Pt, Pd, Rh and Cu - (111) surfaces.55 The PBE functional gave a substantially longer interatomic distance towards the surface as compared to the vdW functionals with a shortest perpendicular C-Au distance of 3.47 Å (PBE), 3.52 Å (vdW-BEEF), 3.48 Å (vdW-DF), 3.38 Å (vdW-DF2), 3.29 Å (optPBE-vdW), 3.18 Å (optB88-vdW), and 3.16 Å 5 ACS Paragon Plus Environment


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(optB86b-vdW), respectively. Other distances, such as, shortest C-H-Au, and O-H-Au are depicted in Figure 1, and for most part these distances follow similar trend, i.e., PBE has the largest values, followed by vdW-BEEF, vdW-DF, vdW-DF2, optPBE-vdW, optB88-vdW, and optB86b-vdW, respectively. The calculated adsorption energies fall into three regimes with the PBE exhibiting the weakest interaction between glycerol and Au(111) (-0.15 eV), followed by vdW-BEEF (-0.39 eV), vdW-DF, vdW-DF2 (-0.49,-0.50 eV), and finally optPBE-vdW (-0.69 eV), optB88-vdW (-0.74 eV), and optB86b-vdW (-0.78 eV). Both structural and energetic results go hand in hand with the treatments of long-range correlation in combination with exchange, i.e. including vdW results in a stronger attraction (smaller distance and higher adsorption energy values), whereas revPBE and rPW86 exchange results in a stronger repulsion as compare to the PBE, B86b, and B88 exchange. This is consistent with the recent calculated data where inclusion of D3 dispersion correction in combination with PBE functional increased glycerol binding energy on Pt (100), (110) and (111) by ~1 eV.54 Glycerol is a large molecule and the results clearly show that long-range correlation is important; however, there is no experimental support as to which density functional is preferred. For example, reported experimental literature data available in the literature for several polyols, including n-hexanol,56 mannitol and sorbitol57 on Au(111) shows value lower than those calculated in this work of -0.23, -0.16 and -0.18 eV, respectively. These experiments, however, were performed in aqueous solution of NaClO4 where nature of the Au(111) surface is likely to be different from that considered in this work. For example, long range superstructures are formed via reconstruction of Au(111) in HClO4 the stability of which depends on the surface potential.58,59 When potential is applied, gold surfaces undergo reactive H2O chemisorption to form hydroxyl radicals, adsorbed gold hydroxide or oxide monolayers.60 Based on the results above and in particular owing the better description of the Au lattice, surface energy, and methanol adsorption61, the main results will be based on optB86bvdW unless explicitly stated otherwise.

Geometric parameters, adsorption energies and electronic structures of glycerol on transition-metal (TM) surface-alloyed Au(111). Bimetallic catalysts are of great importance in organic molecule reforming reactions since they can improve upon the catalytic properties of single metals. For example, Pt/Au bimetallic surfaces yielded adsorption energies much weaker in comparison to Pt alone, thus potentially serving against CO poisoning.62 Non-precious metals, 6 ACS Paragon Plus Environment

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such as Ni have also been used in glycerol electrooxidation.36 To investigate how alloy atoms affect the initial step in the adsorption of glycerol, the Au surface atom that was closed to the interacting OH-group of the glycerol was replaced by a selected 3d-, 4d-, 5d- transition metal atom. These included those routinely used in bimetallic catalyst, such as Sc, Ti, V, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Sn, W, Ir, Pt and Pb, of which most are used to selectively reform organic oxygenate molecules via C-C, C-O and C-H cleavage.63 Coinage metal Cu and Ag aside, Au (111) surface favors the incorporation of alloy atoms in the surface layer, as can be seen in Table 2.

The results are in qualitative agreement with a number of studies using alloyed Au

surfaces.64,65, although it must be recognized that the comparison is not fully justified as we are ignoring important contributions, such as entropy, that would in most cases make the surfacealloyed atom to diffusion into the bulk. Further, Table 2 summaries the calculated adsorption energy of glycerol on bare and single TM atom surface-alloyed Au(111) surface. The values ranged from -0.78 eV (bare Au) to -1.79 eV (Sc/Au) and the increased adsorption energy was associated with a decrease in the binding distance, which shifted by as much as 0.5 Å towards the TM alloy atom. 3rd row TM alloys in general resulted in stronger interaction with the glycerol molecule, e.g. stronger adsorption, whereas other coinage metals, such as Pt, barely increased the adsorption energy. To further rationalize the findings of the dopants, the density of states of the top surface layer, i.e. all 9 surface atoms in the p(3x3) supercell, was analyzed and the results are shown in Figure 2. An immediate and important trend becomes apparent: the more to the left in the periodic table the alloy atoms comes from, the less will the atomic states hybridize with the DOS of Au. This gives rise to a separate DOS component around the Fermi level that is filled to a varying degree depending of the alloy atom. As the d-states occupancy increase, as in the case of Sc to Cu sequence of the 3rd TM row, the overlap with the d-states of Au improves. Calculating the dcenter of the top surface layer, in accordance with the d-band model,51 we find a good correlation with the calculated adsorption energy, as seen in Figure 3. This may be particularly important in designing efficient electro- vs conventional heterogeneous catalysts for organic oxygenate molecule reforming. Enhanced adsorption energy, e.g. stronger metal-O attraction would weaken C-O bond in the glycerol. While this can be beneficial for glycerol reforming to other molecules (Ti, V, Ru, Fe, W), enhanced electrochemical performance of the catalyst requires improved



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deprotonation properties. Hence, Pt, Pd, Sn, Cu can be proposed as efficient alloy atoms to perform electrochemical deprotonation. Vibrational properties of glycerol on Au(111). In situ FTIR measurements have routinely been used to investigate (electro)catalytic oxidation products of glycerol and the assignments are of crucial importance in determining the mechanistic steps of the molecular transformations.28 While most of the experimental studies are done in aqueous solutions, the exception being the gas-phase glycerol spectrum, see Figure 4a 66, FTIR frequency values calculated using vacuum slabs present viable trends in frequency shifts resulting upon coordinative adsorption of the molecules. The vibrational spectra were calculated for gas-phase glycerol, glycerol on Au(111) and on W/Au(111) surfaces. They are shown in Figure 4b, 4c, 4d. Most vibrational eigenvalues are above 700 cm-1 and belong to the surfaceadsorbate vibrations, followed by a number of C-C and C-O internal vibrations of the glycerol. In Figure 5, only the H-O and H-C vibrational modes at high wavenumbers are presented. The vibrational energies for gas-phase glycerolin OH stretching region were in the range of 36243640 cm-1, e.g. almost degenerate, see Figure 5a. They were due to the coupled vibrations between all three hydroxyl groups. Experimental gas-phase glycerol spectrum in Figure 4a showed the OH stretching modes split, possibly due to the averaged configuration conformer or dimer formation.67 Similarly, peaks in C-H stretching region are comprised of five vibrations, three due to the asymmetric stretch and two due to the symmetric stretch located at 2968-2982 cm-1 and 2835-2848 cm-1, respectively. The presence of the surface transformed the three high-lying O-H combination modes into pure O-H modes, as seen in Figure 5b and c, which is in agreement with the tilted adsorbed glycerol structure and the different interatomic distances between the -OH groups and Au(111). Further, on bare Au(111) surface, one of the O-H modes display an upshift of 30 cm-1, together with downshift of ~180 cm-1 and ~260 cm-1 of the two other modes. Similar observation is made on the W/Au surface, e.g. the upshift is ~40 cm-1 for one O-H mode. However, here downshifts of 300 cm-1 and 510 cm-1 were calculated for the other two vibrational modes. This is in contrast to the various C-H modes that exhibit much less perturbation, in most cases less than 20 cm-1. The exception is the symmetric and antisymmetric C-H modes of the end-C-atoms in the glycerol. Interestingly the shifts are opposite to each other depending if it occurs on the bare Au or the W/Au surface. More specifically, the modes are downshifted by 40 cm-1 and 60 cm-1 on bare Au, 8 ACS Paragon Plus Environment

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respectively. On the W/Au(111) surface the same modes are upshifted by 10 cm-1 and 70 cm-1, respectively. There is also a difference in how the surfaces affect the dipole activity of the glycerol modes. In Figure 4 the calculated IR spectra is shown. The calculations display no dipole activity of the highest O-H modes on W/Au, whereas the same modes remain IR active on the bare Au surface. From Figure 4 it is clear that a signature of glycerol adsorption on surface alloy atoms would be the appearance of a dipole active mode with wavenumber around 3100 cm-1 and the associated loss of a dipole active mode around 3650 cm-1. W/Au(111) was used as a case of strongly coordinating surface alloy atom as it provides a clear picture of the molecular transformations. For alloy atoms exhibiting strong overlap with the O-H moiety of glycerol molecule, strong O-H vibrational shifts towards lower wavenumbers are expected as a function of the adsorption energy.

Conclusions and broader impact The glycerol adsorption on Au(111) and Au(111) with substitutional transition metal surface atoms was investigated using first-principles. The results show that geometric and energetic properties depend sensitively on the inclusion of non-local dispersion forces. Evaluating properties such as lattice constant, bulk modules, surface energy, and methanol adsorption for Au, it is clear that optB86b is the preferred dispersion corrected functional, able to describe the system at a sufficient level of accuracy as compared to PBE, vdW-DF, vdW-DF2, optPBE, optB88, optB86b, and vdW-BEEF. Our data, which is based on the optB86b-functional, indicate that the strength of the adsorption between the glycerol molecule and TM surface-alloyed Au(111) correlates well with the d-band center of the surface layer. The vibrational spectra of the adsorbed glycerol also exhibited trends in O-H peak shifts with the increased adsorption energy, as inferred from Au(111) and W/Au(111) calculations, that can be helpful for experimental fingerprinting identification and thus monitoring reactions in situ. More specifically, the O-H modes are sensitive to the surface composition and the calculated IR spectra are distinctly different for the bare Au and W/Au surface. Furthermore, the results provide a handle for improving e.g., the electrooxidation of glycerol by the incorporation of transition-metal atoms, by modifying the adsorption energy.

Acknowledgments 9 ACS Paragon Plus Environment


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Support from the Swedish Research Council, Formas, and the Chalmers Area of Advance Material and Energy are acknowledged. Partial financial support from Lehigh University is also gratefully acknowledged. The calculations were performed at NSC (Linköping).


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References

(1)

Ruhal, R.; Aggarwal, S.; Choudhury, B. Suitability of Crude Glycerol Obtained from Biodiesel Waste for the Production of Trehalose and Propionic Acid. Green Chem. 2011, 13, 3492–3498.

(2)

Yang, F.; Hanna, M. A.; Sun, R. Value-Added Uses for Crude Glycerol--a Byproduct of Biodiesel Production. Biotechnol. Biofuels 2012, 5, 13.

(3)

Kenar, J. A. Glycerol as a Platform Chemical: Sweet Opportunities on the Horizon? Lipid Technol. 2007, 19, 249–253.

(4)

Wang, B.; Shen, Y.; Sun, J.; Xu, F.; Sun, R. Conversion of Platform Chemical Glycerol to Cyclic Acetals Promoted by Acidic Ionic Liquids. RSC Adv. 2014, 4, 18917–18923.

(5)

Kamm, B. Production of Platform Chemicals and Synthesis Gas from Biomass. Angew. Chemie Int. Ed. 2007, 46, 5056–5058.

(6)

Zhou, C.-H. (Clayton); Beltramini, J. N.; Fan, Y.-X.; Lu, G. Q. (Max). Chemoselective Catalytic Conversion of Glycerol as a Biorenewable Source to Valuable Commodity Chemicals. Chem. Soc. Rev. 2008, 37, 527–549.

(7)

Katryniok, B.; Paul, S.; Belliere-Baca, V.; Rey, P.; Dumeignil, F. Glycerol Dehydration to Acrolein in the Context of New Uses of Glycerol. Green Chem. 2010, 12, 2079–2098.

(8)

Katryniok, B.; Kimura, H.; Skrzynska, E.; Girardon, J.-S.; Fongarland, P.; Capron, M.; Ducoulombier, R.; Mimura, N.; Paul, S.; Dumeignil, F. Selective Catalytic Oxidation of Glycerol: Perspectives for High Value Chemicals. Green Chem. 2011, 13, 1960–1979.

(9)

Nakagawa, Y.; Tomishige, K. Heterogeneous Catalysis of the Glycerol Hydrogenolysis. Catal. Sci. Technol. 2011, 1, 179–190.

(10)

Liu, S.-K.; Lin, Y.-C. Autothermal Partial Oxidation of Glycerol to Syngas over Pt-, LaMnO3-, and Pt/LaMnO3-Coated Monoliths. Ind. Eng. Chem. Res. 2012, 51, 16278– 16287.

(11)

Skoplyak, O.; Barteau, M. A.; Chen, J. G. Enhancing H2 and CO Production from Glycerol Using Bimetallic Surfaces. ChemSusChem 2008, 1, 524–526. 11 ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 26

(12)

Lin, Y.-C. Catalytic Valorization of Glycerol to Hydrogen and Syngas. Int. J. Hydrogen Energy 2013, 38, 2678–2700.

(13)

Cheng, W.; Singh, N.; Maciá-Agulló, J. A.; Stucky, G. D.; McFarland, E. W.; Baltrusaitis, J. Optimal Experimental Conditions for Hydrogen Production Using Low Voltage Electrooxidation of Organic Wastewater Feedstock. Int. J. Hydrogen Energy 2012, 37, 13304–13313.

(14)

Lu, X.; Xie, S.; Yang, H.; Tong, Y.; Ji, H. Photoelectrochemical Hydrogen Production from Biomass Derivatives and Water. Chem. Soc. Rev. 2014, 43, 7581–7593.

(15)

Qi, J.; Xin, L.; Chadderdon, D. J.; Qiu, Y.; Jiang, Y.; Benipal, N.; Liang, C.; Li, W. Electrocatalytic Selective Oxidation of Glycerol to Tartronate on Au/C Anode Catalysts in Anion Exchange Membrane Fuel Cells with Electricity Cogeneration. Appl. Catal. B Environ. 2014, 154–155, 360–368.

(16)

Gomes, J. F.; Gasparotto, L. H. S.; Tremiliosi-Filho, G. Glycerol Electro-Oxidation over Glassy-Carbon-Supported Au Nanoparticles: Direct Influence of the Carbon Support on the Electrode Catalytic Activity. Phys. Chem. Chem. Phys. 2013, 15, 10339–10349.

(17)

Padayachee, D.; Golovko, V.; Ingham, B.; Marshall, A. T. Influence of Particle Size on the Electrocatalytic Oxidation of Glycerol over Carbon-Supported Gold Nanoparticles. Electrochim. Acta 2014, 120, 398–407.

(18)

Demirel, S.; Lehnert, K.; Lucas, M.; Claus, P. Use of Renewables for the Production of Chemicals: Glycerol Oxidation over Carbon Supported Gold Catalysts. Appl. Catal. B Environ. 2007, 70, 637–643.

(19)

Wang, D.; Villa, A.; Su, D.; Prati, L.; Schlögl, R. Carbon-Supported Gold Nanocatalysts: Shape Effect in the Selective Glycerol Oxidation. ChemCatChem 2013, 5, 2717–2723.

(20)

Zhao, Z.; Arentz, J.; Pretzer, L. A.; Limpornpipat, P.; Clomburg, J. M.; Gonzalez, R.; Schweitzer, N. M.; Wu, T.; Miller, J. T.; Wong, M. S. Volcano-Shape Glycerol Oxidation Activity of Palladium-Decorated Gold Nanoparticles. Chem. Sci. 2014, 5, 3715–3728.

(21)

Carrettin, S.; McMorn, P.; Johnston, P.; Griffin, K.; Hutchings, G. J. Selective Oxidation of Glycerol to Glyceric Acid Using a Gold Catalyst in Aqueous Sodium Hydroxide. Chem. Commun. 2002, 696–697. 12 ACS Paragon Plus Environment

Page 13 of 26

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(22)

Sobczak, I.; Jagodzinska, K.; Ziolek, M. Glycerol Oxidation on Gold Catalysts Supported on Group Five Metal oxides—A Comparative Study with Other Metal Oxides and Carbon Based Catalysts. Catal. Today 2010, 158, 121–129.

(23)

Prati, L.; Spontoni, P.; Gaiassi, A. From Renewable to Fine Chemicals Through Selective Oxidation: The Case of Glycerol. Top. Catal. 2009, 52, 288–296.

(24)

Bianchi, C. L.; Canton, P.; Dimitratos, N.; Porta, F.; Prati, L. Selective Oxidation of Glycerol with Oxygen Using Mono and Bimetallic Catalysts Based on Au, Pd and Pt Metals. Catal. Today 2005, 102–103, 203–212.

(25)

Brett, G. L.; He, Q.; Hammond, C.; Miedziak, P. J.; Dimitratos, N.; Sankar, M.; Herzing, A. A.; Conte, M.; Lopez-Sanchez, J. A.; Kiely, C. J.; et al. Selective Oxidation of Glycerol by Highly Active Bimetallic Catalysts at Ambient Temperature under Base-Free Conditions. Angew. Chemie Int. Ed. 2011, 50, 10136–10139.

(26)

Maris, E. P.; Ketchie, W. C.; Murayama, M.; Davis, R. J. Glycerol Hydrogenolysis on Carbon-Supported PtRu and AuRu Bimetallic Catalysts. J. Catal. 2007, 251, 281–294.

(27)

Angelucci, C. A.; Varela, H.; Tremiliosi-Filho, G.; Gomes, J. F. The Significance of NonCovalent Interactions on the Electro-Oxidation of Alcohols on Pt and Au in Alkaline Media. Electrochem. commun. 2013, 33, 10–13.

(28)

Gomes, J.; Tremiliosi-Filho, G. Spectroscopic Studies of the Glycerol Electro-Oxidation on Polycrystalline Au and Pt Surfaces in Acidic and Alkaline Media. Electrocatalysis 2011, 2, 96–105.

(29)

Hanke, F.; Björk, J. Structure and Local Reactivity of the Au(111) Surface Reconstruction. Phys. Rev. B 2013, 87, 235422.

(30)

Björk, J.; Stafström, S. Adsorption of Large Hydrocarbons on Coinage Metals: A van Der Waals Density Functional Study. ChemPhysChem 2014, 15, 2851–2858.

(31)

Bedolla, P. O.; Feldbauer, G.; Wolloch, M.; Eder, S. J.; Dörr, N.; Mohn, P.; Redinger, J.; Vernes, A. Effects of van Der Waals Interactions in the Adsorption of Isooctane and Ethanol on Fe(100) Surfaces. J. Phys. Chem. C 2014, 118, 17608–17615.

(32)

Tonigold, K.; Groß, A. Adsorption of Small Aromatic Molecules on the (111) Surfaces of Noble Metals: A Density Functional Theory Study with Semiempirical Corrections for Dispersion Effects. J. Chem. Phys. 2010, 132, -. 13 ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 26

(33)

Grimme, S. Semiempirical GGA-Type Density Functional Constructed with a Long-Range Dispersion Correction. J. Comput. Chem. 2006, 27, 1787–1799.

(34)

McNellis, E. R.; Meyer, J.; Reuter, K. Azobenzene at Coinage Metal Surfaces: Role of Dispersive van Der Waals Interactions. Phys. Rev. B 2009, 80, 205414.

(35)

Dion, M.; Rydberg, H.; Schröder, E.; Langreth, D. C.; Lundqvist, B. I. Van Der Waals Density Functional for General Geometries. Phys. Rev. Lett. 2004, 92, 246401.

(36)

Oliveira, V. L.; Morais, C.; Servat, K.; Napporn, T. W.; Tremiliosi-Filho, G.; Kokoh, K. B. Glycerol Oxidation on Nickel Based Nanocatalysts in Alkaline Medium – Identification of the Reaction Products. J. Electroanal. Chem. 2013, 703, 56–62.

(37)

Kresse, G.; Furthmüller, J. Efficiency of Ab-Initio Total Energy Calculations for Metals and Semiconductors Using a Plane-Wave Basis Set. Comput. Mater. Sci. 1996, 6, 15–50.

(38)

Kresse, G.; Furthmüller, J. Efficient Iterative Schemes for ab Initio Total-Energy Calculations Using a Plane-Wave Basis Set. Phys. Rev. B 1996, 54, 11169–11186.

(39)

Kresse, G.; Hafner, J. Ab Initio Molecular Dynamics for Open-Shell Transition Metals. Phys. Rev. B 1993, 48, 13115–13118.

(40)

Kresse, G.; Hafner, J. Ab Initio Molecular-Dynamics Simulation of the Liquid-Metal Amorphous-Semiconductor Transition in Germanium. Phys. Rev. B 1994, 49, 14251– 14269.

(41)

Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865–3868.

(42)

Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1997, 78, 1396.

(43)

Klimeš, J.; Bowler, D. R.; Michaelides, A. Van Der Waals Density Functionals Applied to Solids. Phys. Rev. B 2011, 83, 195131.

(44)

Klimeš, J.; Bowler, D. R.; Michaelides, A. Chemical Accuracy for the van Der Waals Density Functional. J. Phys. Condens. Matter 2010, 22, 22201. 14 ACS Paragon Plus Environment

Page 15 of 26

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(45)

Lee, K.; Murray, É. D.; Kong, L.; Lundqvist, B. I.; Langreth, D. C. Higher-Accuracy van Der Waals Density Functional. Phys. Rev. B 2010, 82, 81101.

(46)

Wellendorff, J.; Lundgaard, K. T.; Møgelhøj, A.; Petzold, V.; Landis, D. D.; Nørskov, J. K.; Bligaard, T.; Jacobsen, K. W. Density Functionals for Surface Science: ExchangeCorrelation Model Development with Bayesian Error Estimation. Phys. Rev. B 2012, 85, 235149.

(47)

Kresse, G.; Joubert, D. From Ultrasoft Pseudopotentials to the Projector Augmented-Wave Method. Phys. Rev. B 1999, 59, 1758–1775.

(48)

Blöchl, P. E. Projector Augmented-Wave Method. Phys. Rev. B 1994, 50, 17953–17979.

(49)

Monkhorst, H. J.; Pack, J. D. Special Points for Brillouin-Zone Integrations. Phys. Rev. B 1976, 13, 5188–5192.

(50)

Porezag, D.; Pederson, M. R. Infrared Intensities and Raman-Scattering Activities within Density-Functional Theory. Phys. Rev. B 1996, 54, 7830–7836.

(51)

Hammer, B.; Nørskov, J. K. Theoretical Surface Science and Catalysis—calculations and Concepts. In Impact of Surface Science on Catalysis; Bruce C. Gates, H. K. B. T.-A. in C., Ed.; Academic Press, 2000; Vol. Volume 45, pp 71–129.

(52)

Gong, J.; Flaherty, D. W.; Ojifinni, R. A.; White, J. M.; Mullins, C. B. Surface Chemistry of Methanol on Clean and Atomic Oxygen Pre-Covered Au(111). J. Phys. Chem. C 2008, 112, 5501–5509.

(53)

Tyson, W. R.; Miller, W. A. Surface Free Energies of Solid Metals: Estimation from Liquid Surface Tension Measurements. Surf. Sci. 1977, 62, 267–276.

(54)

Tereshchuk, P.; Chaves, A. S.; Da Silva, J. L. F. Glycerol Adsorption on Platinum Surfaces: A Density Functional Theory Investigation with van Der Waals Corrections. J. Phys. Chem. C 2014, 118, 15251–15259.

(55)

Liu, B.; Greeley, J. A Density Functional Theory Analysis of Trends in Glycerol Decomposition on Close-Packed Transition Metal Surfaces. Phys. Chem. Chem. Phys. 2013, 15, 6475–6485. 15 ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(56)

Sottomayor, M. J.; Coelho, V.; Ferreira, A. P.; Silva, F.; Baturina, O. A.; Safonov, V. A.; Damaskin, B. B. Parameters of N-Hexanol Adsorption on Au (111). Comparison between Differential Capacity and Chronocoulometry Results. Electrochim. Acta 1999, 45, 775– 787.

(57)

Sottomayor, M. J.; Silva, F. Adsorption of Mannitol and Sorbitol on gold(111). J. Electroanal. Chem. 1994, 376, 59–64.

(58)

Tao, N. J.; Lindsay, S. M. Observations of the 22×√3 Reconstruction of Au(111) under Aqueous Solutions Using Scanning Tunneling Microscopy. J. Appl. Phys. 1991, 70.

(59)

Gao, X.; Hamelin, A.; Weaver, M. J. Atomic Relaxation at Ordered Electrode Surfaces Probed by Scanning Tunneling Microscopy: Au(111) in Aqueous Solution Compared with Ultrahigh‐vacuum Environments. J. Chem. Phys. 1991, 95.

(60)

Lertanantawong, B.; O’Mullane, A. P.; Surareungchai, W.; Somasundrum, M.; Burke, L. D.; Bond, A. M. Study of the Underlying Electrochemistry of Polycrystalline Gold Electrodes in Aqueous Solution and Electrocatalysis by Large Amplitude Fourier Transformed Alternating Current Voltammetry. Langmuir 2008, 24, 2856–2868.

(61)

Egeberg, R. C.; Chorkendorff, I. Improved Properties of the Catalytic Model System Ni/Ru(0001). Catal. Letters 2001, 77, 207–213.

(62)

Ren, H.; Humbert, M. P.; Menning, C. A.; Chen, J. G.; Shu, Y.; Singh, U. G.; Cheng, W.C. Inhibition of Coking and CO Poisoning of Pt Catalysts by the Formation of Au/Pt Bimetallic Surfaces. Appl. Catal. A Gen. 2010, 375, 303–309.

(63)

Davda, R. R.; Shabaker, J. W.; Huber, G. W.; Cortright, R. D.; Dumesic, J. A. AqueousPhase Reforming of Ethylene Glycol on Silica-Supported Metal Catalysts. Appl. Catal. B Environ. 2003, 43, 13–26.

(64)

Greeley, J.; Nørskov, J. K. A General Scheme for the Estimation of Oxygen Binding Energies on Binary Transition Metal Surface Alloys. Surf. Sci. 2005, 592, 104–111.

(65)

Fajín, J. L. C.; Cordeiro, M. N. D. S.; Gomes, J. R. B. DFT Study on the Reaction of O2 Dissociation Catalyzed by Gold Surfaces Doped with Transition Metal Atoms. Appl. Catal. A Gen. 2013, 458, 90–102.

(66)

Linstrom, P. J.; Mallard, W. G. NIST Mass Spec Data Center, S.E. Stein, Director, “Infrared Spectra” in NIST Chemistry WebBook, NIST Standard Reference Database 16 ACS Paragon Plus Environment

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Number 69. (67)

Bell, F.; Ruan, Q. N.; Golan, A.; Horn, P. R.; Ahmed, M.; Leone, S. R.; Head-Gordon, M. Dissociative Photoionization of Glycerol and Its Dimer Occurs Predominantly via a Ternary Hydrogen-Bridged Ion–Molecule Complex. J. Am. Chem. Soc. 2013, 135, 14229– 14239.



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Table 1. Bulk Au lattice constant, Å, bulk modulus, GPa, surface energy, J/m2, methanol adsorption energy, eV, calculated using several exchange correlation and dispersion correction methods Exchange correlation

Surface energy Methanol Au lattice J/m2 adsorption constant, energy, eV Å Bulk modulus, GPa

Experimental

4.078

220.0

1.5053

-0.4252

PBE

4.174

137.2

0.69

-0.12

optB86-vdW

4.138

155.2

1.09

-0.45

optB88-vdW

4.177

140.3

0.97

-0.44

optPBE-vdW

4.197

130.2

0.89

-0.42

vdW-DF

4.252

108.2

0.75

-0.32

vdW-DF2

4.343

87.3

0.68

-0.34

vdW-BEEF

4.225

114.5

0.79

-0.26+-0.20


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Table 2. Tabulated alloying energies (Ealloy, eV), magnetic moments and glycerol adsorption energies (Eads, eV) on transition-metal surface alloyed Au(111) surface Atomic number 21 22 23 26 27 28 29 44 45 46 47 50 74 77 78 79 82

Alloy atoma Sc Ti V Fe Co Ni Cu Ru Rh Pd Ag Sn W Ir Pt Au Pb

Ealloy, eV -3.05 -2.61 -1.67 -0.72 -0.84 -0.98 0.06 -2.26 -1.89 -0.70 0.50 -0.85 -2.88 -2.90 -2.24 0.00 -0.61

Magnetic moment 0.00 0.41 3.09 3.26 1.84 0.00 0.05 1.12 0.04 0.00 0.05 0.07 1.62 0.04 0.04 0.00 0.00

Eads, eV -1.79 -1.72 -1.62 -1.24 -1.20 -1.08 -0.99 -1.38 -1.11 -0.89 -0.88 -0.99 -1.75 -1.17 -0.85 -0.78 -1.03

Glycerol O-TM alloy distance, Å 2.14 2.10 2.16 2.11 2.21 2.07 2.16 2.19 2.25 2.43 2.48 2.48 2.15 2.21 2.43 2.65 2.65

a. Alloy energy, Ealloy, calculated as (EAu(111)alloy+EAu atom)-(EAu(111)+Ealloy atom)



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Figures Figure 1. Top layer structural models of glycerol adsorbed on Au(111) for different combination of functionals and dispersion corrections (PBE, optB86b-vdW, optB88-vdW, optPBE-vdW, vdW-DF, vdW-DF2, vdW-BEEF). The corresponding adsorption energies, Eads (eV) are also shown. Purple atoms represent the top layer of the Au(111) surface slab modelled. Figure 2. Calculated DOS plots for the bare and transition metal alloyed Au(111) surface. Fermi level corresponds to 0 eV and occupied levels are shaded. Figure 3. Glycerol adsorption energy (eV) on transition metal alloyed Au(111) surface as a function of the calculated d-band center (eV). Line is added for the eye guidance only. d-band center was calculated for the top surface layer of the structure only. Figure 4. Spectra of (a) experimentally obtained gas-phase glycerol66, (b) calculated gas-phase glycerol, (c) glycerol adsorbed on Au(111) and (d) glycerol adsorbed on W/Au(111). Lorentzian broadening of 50 cm-1 was applied to generate the spectra. Figure 5.

Vibrational displacements for (a) calculated gas-phase glycerol, (b) glycerol on

Au(111) and finally (c) glycerol on W/Au(111). Magnitude of the arrow size is proportional to the displacement. Blue atom represents the W alloy atom. Vibrational frequency is also shown in cm-1.


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Figure 1



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Figure 2 22 ACS Paragon Plus Environment

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Figure 3



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Figure 4


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(a)

(b)

(c)

Figure 5



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Electronic properties of TM doped Au(111) interacting with glycerol (Eads, d-band, IR shift) are best represented using optB86b-vdW functional.


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Geometry and Electronic Properties of Glycerol Adsorbed on Bare and

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